The Storm Prediction Center predicted a moderate risk of severe weather (link) over the southern Plains of the US on 15 June 2023. The animation above shows surface-based CAPE derived from 4-km WRF model output. This model incorporates information from Polar Hyperspectral Soundings via the Fusion process. Model CAPE fields are overlain by NOAA/CIMSS ProbSevere (version 3) polygons from 1700-2000 UTC. There is good agreement for those times between the gradient of the CAPE fields and the location of the ProbSevere polygons that show were severe weather is most likely. The 2100 UTC image of surface-based CAPE is also shown. Where do you think the polygons will be at 2100 UTC? That is shown below. These model fields can help with situational awareness in the near-term. (Model output is available at this link).

A particular benefit of the PHS model output fields shown above is that they are high-resolution, that information is available in cloudy and clear regions and that the forecast provides short-term (that is, 0-9 hour) guidance. Other satellite-based stability products are available of course. The two-panel below shows PHS output and GOES-16 Derived Stability Index estimates of CAPE. The character and gradients of the fields are very similar — but the Level-2 GOES estimate is created only in regions of clear skies. A direct (toggled) comparison of the fields at 1900 UTC is here. The comparison between the real-time GOES estimates and the 5-h model field suggests that the model evolution is just a bit slow.

NOAA-20 overflew the eastern part of this domain at around 1900 UTC, and gridded NUCAPS fields of temperature and moisture were used to diagnose the stability. That is shown below. As with the PHS-enhanced WRF model output, NUCAPS fields give information in clear and cloudy regions. The horizontal resolution of NUCAPS data, however, is around 50 km; the display of tight gradients is a challenge.

The toggle below shows Sounding Availability points (Green Points: infrared retrieval converged to a solution; Yellow Points: microwave retrieval converged to a solution; Red Points: neither infrared nor microwave retrieval converged), the Total Totals index, and the lapse rate from 700-500 mb. The Total Totals index suggests the strongest instability over western Oklahoma, a region with steep 700-500 mb lapse rates.

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The PHSnMWnABI model output (and Probsevere Version 3) were both evaluated at SPC’s Hazardous Weather Testbed within the past month. Blog Posts from the forecasters that describe how these products can be used are here. SPC storm reports for this day are shown below. They do align with satellite estimates of CAPE.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) plots of SPC Storm Reports (above) showed thunderstorms that produced several tornadoes, hail as large as 5.00 inches in diameter, and damaging winds to 82 mph across parts of Mississippi, Alabama, Georgia and Florida on 14 June 2023. Pulses of overshooting tops exhibited infrared brightness temperatures in the -70ºC to -80ºC range.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) plots of SPC Storm Reports (above) showed thunderstorms that produced hail as large as 4.50 inches in diameter, damaging winds to 71 mph and a tornado across parts of New Mexico, Texas and Oklahoma from the late afternoon into the subsequent nighttime hours on 11 June 2023.

In a closer look at 1-minute GOES-16 Infrared images over the Dallas-Fort Worth, Texas area (rawinsonde site KFWD) from 0000-0200 UTC on 12 June (below), several overshooting top pulses became surrounded by brief “warm trench” signatures — a likely indication of compensating subsidence around the periphery of these vigorous updrafts as they rapidly ascended past the local equilibrium level and/or tropopause. The coldest overshooting top exhibited an infrared brightness temperature of -87.6ºC at 0115 UTC.

Comparisons of GOES-16 Infrared image, CLAVR-x Cloud Top Height and Operational Cloud Top Height for overshooting tops with surrounding “warm trench” signatures in Tarrant County and Denton County at 0106 UTC, 0116 UTC and 0121 UTC are shown below —  note how the full-resolution (nominal 2-km) CLAVR-x Cloud Top Height products (created at CIMSS) more accurately depicted the overshooting top and surrounding warm trench features, which were not as apparent in the 10-km resolution Operational Cloud Top Height products that are currently distributed to AWIPS users.

When comparing cursor-sampled values of Cloud Top Height for the coldest portion of overshooting tops in Tarrant and Denton County (below), the CLAVR-x values were always significantly higher (14.9 kft to 16.8 kft higher) — since the CLAVR-x higher spatial resolution more accurately depicted the size and location of the overshooting tops (as seen in the Infrared images).

However, cursor-sampled Cloud Top Height values within the corresponding warm trench features were generally similar (below), although the CLAVR-x values were usually several hundred feet lower than the Operational values.

The largest CLAVR-x Cloud Top Height difference between an overshooting top and its surrounding warm trench was 19,431 feet (over Tarrant County at 0116 UTC, shown below) — the corresponding lower spatial resolution Operational Cloud Top Height difference was only 2973 feet!

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Cyclone Biparjoy in the Arabian Sea began a period of rapid intensification late in the day on 09 June 2023, reaching Category 3 intensity by 12 UTC on 10 June (SATCON) — EUMETSAT Meteosat-9 Visible (0.64 µm) and Infrared Window (10.8 µm) images (above) showed Biparjoy during the 0100-1330 UTC period on 10 June 2023. A somewhat cloud-contaminated eye signature was evident in both the Visible and Infrared Meteosat-9 images, in addition to a Suomi-NPP VIIRS True Color RGB image (viewed using RealEarth) valid at 0747 UTC (below).

The Category 3 intensity of Biparjoy was supported by 2 overpasses of RADARSAT Constellation Mission (RCM)-3 at 0125 UTC (above) and 1337 UTC (below) — with peak Synthetic Aperture Radar (SAR) radial wind velocities of 106 knots in the SE quadrant at 0125 UTC and 105 knots in the SE quadrant at 1337 UTC (source).

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